Heat generators



june 28, 1966 Filed Jan. l5, 1964 2 Sheets-Sheet l ATTORNEY June 28,1966 Filed Jan. l5, 1964 A. WILSON ET AL HEAT GENERATORS 2 Sheets-Sheet2 ATTORNEY United States Patent 3,258,052 HEAT GENERATORS Alfred Wilson,lilognor Regis, and Charles J. G. Green and David ll. OReilly, Havant,England, assignors to Colt Ventilation and Heating Limited Filed 1an.15, 1964, Ser. No. 337,908 Claims priority, application /regat Britain,Jan. 18, 1963,

9 2 Claims. (Cl. 158-1) This invention concerns heat generatorscomprising a heat exchanger chamber `and a liqoid or gaseous fuelburner, the heat developed in the chamber being used eg. to heat airutilised for space heating in factories, oices, warehouses and so on.

According to this invention a heat generator comprises an elongated heatexchanger chamber having confronting end wall and a side walltherebetween which is substantially ya surface of revolution about thelongitudinal axis of the chamber, a liquid or gas burner carriedsubstantially centrally of one end wall of the chamber and directedlengthwise thereof towards the opposite end wall, said lburner beingconstructed and arranged to produce a llame which extends forwardly intothe chamber and which is spaced substantially from the side wall of thechamber and ports in the chamber-for the discharge of combustionproducts-said ports being behind and radially outwardly of the llamewhereby the hot gases are circulated within the chamber, firstly, as astream lengthwise of the chamber and substantially centrally thereoftowards said opposite end wall and, secondly, as -a stream in thereverse direction over the side wall and past the llame towards theport, some of the second stream of gases being entrained as it passesthe flame and being re-circulated, the remainder of the gases beingdischarged through the ports.

A practical application of the present invention is shown by way ofexample in the accompanying drawings of which FIG. 1 is a schematicsectional elevation of the heat generator and FIG. 2 is a View in thedirection of the arrow A of FIG. 1.

For convenience the generator is assumed to be vertically disposedthough of course it may be arranged in any other convienient way.

The heat exchanger chamber 5 5 which is preferably circular-comprises aside wall 6, a lower end wall 8 and an opposite, upper end wall 7. Thelower end wall 8 carries an oil burner generally indicated at 9. Asuitable gas burner may be used instead. Ports 10 are provided in theside wall 6 around the burner 9. The ports 10 lare uniformly spacedaround the combustion chamber (FIG. 2) and are :provided for thedischarge of combustion products as later more fully described. Theports 10 are referred to for convenience as exhaust ports.

The heat exchanger chamber is surrounded by a jacket 11 which providesan air space 12 around the chamber 5. Air is forced (c g. by a fan-notshown) upwardly through space 12 between jacket 11 and heat exchangerchamber 5 thereby becoming heated. The jacket 11 surrounding chamber 5constitutes the heat exchanger referred to above. This may be a primaryheat exchanger, the air discharged at 13 and the combustion gasesdelivered through exhaust ports 10 being passed to a secondary heatexchanger, or in succession to several heat exchangers as required.

Referring now to the burner 9: the central axis of the burner coincideswith the longitduinal axis of the chamber 5 (see FIG. 2). The burner 9comprises an atomiser nozzel 14 supplied with fuel oil under pressurethrough pipe 15. Atomised fuel is sprayed upwardly into a combustionchamber f16 which is extended axially to form a llame discharge cone 17constituting a neck means which is convergent in the ydirection of flamepropagation and projects to a limited extent into the heat exchangerchamber 5. A cylindrical casing 18 surrounds, and is spaced from,chamber 16 and is in turn surrounded, and spaced from, outer casing 19of the burner 9. Combustion air delivered to the burner by pipe 2i)passes upwardly around casing 18 and is then reverted to flow downwardlywithin casing 18. The downwardlyflowing air passes into chamber 16through slots 21, 22 and holes 23. The air flowing within burner 9 asindicated is thus pre-heated before entering chamber 16. The slots 21,22 impart rotation to the air passing therethrough, the Iair beingrotated in opposite directions.

The burner 9 is fitted with electric igniters 24 which, in known manner,are connected to any convenient electric supply.

Air and fuel oil is supplied to the burner 9 to produce a flame which issubstantially within the projected diameter a-a of burner 9, so that themaximum width of the flame within the heat exchanger chamber 5 issubstantially equal to the width of the combustion chamber 16, and it istherefore spaced substantially from the side wall 6. Its axial extentforwardly of wall 8 is relatively short with the result that, for arelatively short heat exchanger chamber, as measured axially, and for achamber of relatively small diameter, a relatively large air space 25 isprovided around the flame. It is imperative for the satisfactory workingof this invention that there is a relatively large space between theflame and the wall 6 and that the ports 10 are radially outwardly of theflame (ie. radially outside the projected diameter a) and that they arebehind the flame-as is apparent from FIG. l. However, while it may bepreferred that the flame be short axially this is not essential and incertain circumstances it may come very close to, or impinge upon, theend wall 7. In practice the flame width is approximately betweenone-third and one-half of the diameter of chamber 5.

In use: the hot gases flow with a relatively high local velocity causedat the llame discharge end of the cone 17 axially along chamber 5 andcentrally thereof from the flame towards end wall 7. This is Aindicatedby the arrows 26. Near wall 7 the gases are deflected outwardly (at 27)and return (as shown by arrows 28) along the side wall 6, constrainingthe axial stream from contact therewith. Around the llame thecirculating stream of hot gases divides-some escape through ports 10(arrows 29) and the remainer is entrained (arrow 30) by the flame due tothe high local velocity adjacent the cone 17 and again liows in thedirection of arrows 26. By this means a large quantity of the gases arecontinuously re-circulated so that the time during which the gasesremain in the heat exchanger chamber is prolonged (and thereby greateruse is made of the gases in heat exchange). The hottest gases form acentral core extending axially of chamber 5 towards end wall 7. Therelatively cooler gases sweep continuously over the side wall 6. Thesegases are at a temperature acceptable by the wall mat-terial and theyforrn an annular blanket surrounding the central core and shielding thewall 6 from the core. There is no part of the chamber 5 exposed directlyto the llame; the walls of the chamber are swept by gases at arelatively uniform temperature so that the walls are themselves at auniform temperature and there is a high degree of heat transfer throughthe walls.

The flame and the hot gases therefrom are not permitted to pass directlyto the exhaust ports-which reduces the duration of residence of the hotgases Ain the chamber and therefore prevents an optimum amount of heatbeing extracted from them in heat exchange. This result is achieved byarranging the ports in relation to the llame so that partialre-circulation is achieved.

The air How-ing through space 12 passes around ports 10 before owingover the wall 6. Thus, the air at its lowest temperature is available tocool the ports 10. Also, of course, the gases passing through the portsfrom chamber 5 have been cooled within the chamber and are not at anexcessive temperature.

Any other suitable construction of burner may be used. For example, theburner may comprise an atomiser for liquid fuel and means for supplyinga stream of air which rotates or swirls around the burner axis. Theswirling stream of air and the fuel pass axially through thesmaller-diameter end of a conical chamber having a cylindrical wall atits larger end to constrain the sideways spread of the llame.

We claim:

1. A heat generator comprising a heat exchanger chamber havingconfronting end walls and a side wall extending therebetween about alongitudinal axis of the chamber, a burner carried substantiallycentrally of one of said end walls of the heat exchanger chamber anddirected lengthwise of such chamber towards the opposite end wall, saidburner including a combust-ion chamber and wall means dening a flamedischarge cone which forms an axial extension of the combustion chamber,which wall means is both internally and externally convergent towardsthe mouth of the cone in the direction of the llame propagation andprojects to a limited extent into the heat exchanger chamber such as toproduce a flame which extends forwardly from said mouth into the heatexchanger chamber and which is spaced substantially from the side wallthereof, and exhaust porting for the discharge of combustion productsfrom the heat exchanger chamber located in the side wall adjacent saidone end wall, the construction and arrangement being such that the hotcombustion gases are circulated Within the heat exchanger chamber rstlyals a stream lengthwise of the chamber and substantially centrallythereof from said mouth towards said opposite end wall and .secondly asa stream in the reverse direction along said side wall and constrainingthe rst stream from contact with the side wall, the second stream beingcaused to divide radially outwards of said cone and radially inwards ofsaid porting with a substantial proportion becoming entrained radiallyinwardly into the rst stream and the remainder owing to a dischargethrough said porting.

2. A heat generator according to claim 1 wherein the maximum width ofthe flame within the heat exchanger chamber is substantially equal tothe width of the combustion chamber, and such width is approximatelybetween one-third and one-half of the width of the heat exchangerchamber.

References Cited by the Examiner UNITED STATES PATENTS 1,666,367 4/1928Clausing. 2,072,048 2/1937 Leonard 126-95 2,389,027 1l/1945 Corbin etal. 2,453,029 11/1948 Mills 158--91 2,638,745 5/1953 Nathan 158--l.5 X2,645,278 7/1953 Holthouse 126-110 X 2,993,479 7/ 1961 Thurley et al.

FOREIGN PATENTS 876,161 8/1961 Great Britain.

CHARLES I. MYI-IRE, Primary Examiner.

JAMES W. WESTHAVER, FREDERICK L. MATTE- SON, Examiners.

1. A HEAT GENERATOR COMPRISING A HEAT EXCHANGER CHAMBER HAVINGCONFRONTING END WALLS AND A SIDE WALL EXTENDING THEREBETWEEN ABOUT ALONGITUDINAL AXIS OF THE CHAMBER, A BURNER CARRIED SUBSTANTIALLYCENTRALLY OF ONE OF SAID END WALLS OF THE HEAT EXCHANGER CHAMBER ANDDIRECTED LENGTHWISE OF SUCH CHAMBER TOWARDS THE OPPOSITE END WALL, SAIDBURNER INCLUDING A COMBUSTION CHAMBER AND WALL MEANS DEFINING A FLAMEDISCHARGE CONE WHICH FORMS AN AXIAL EXTENSION OF THE COMBUSTION CHAMBER,WHICH WALL MEANS IS BOTH INTERNALLY AND EXTERNALLY CONVERGENT TOWARDSTHE MOUTH OF THE CONE IN THE DIRECTION OF THE FLANGE PROPAGATION ANDPROJECTS TO A LIMITED EXTENT INTO THE HEAT EXCHANGER CHAMBER SUCH AS TOPRODUCE A FLAME WHICH EXTENDS FORWARDLY FROM SAID MOUTH INTO THE HEATEXCHANGER CHAMBER AND WHICH IS SPACED SUBSTANTIALLY FROM THE SIDE WALLTHEREOF, AND EXHAUST PORTING FOR THE DISCHARGE OF COMBUSTION PRODUCTSFROM THE HEAT EXCHANGER CHAMBER LOCATED IN THE SIDE WALL ADJACENT SAIDONE END WALL, THE CONSTRUCTION AND ARRANGEMENT BEING SUCH THAT THE HOTCOMBUSTION GASES ARE CIRCULATED WITHIN THE HEAT EXCHANGER CHAMBERFIRSTLY AS A STREAM LENGTH-